With Blu-ray Discs, which are next-generation optical discs, as with ordinary optical discs, a protective film comprising a polycarbonate resin for protecting an information recording layer is bonded to the information recording layer; however, Blu-ray Discs have a very high capacity and high density of recorded information, and hence errors may occur in reading or writing of information if the protective film is damaged even only slightly, and thus the present state of affairs is that Blu-ray Discs are handled while housed in a cartridge.
However, to make Blu-ray Discs more compact as media and to reduce the manufacturing cost, cartridge-less bare discs are desired.
Therefore, forming a hard coating layer 12P on the protective film 11 for the information recording layer has, for example, been proposed as shown in FIG. 4 (Japanese Patent Application Laid-open No. 2002-245672).
The protective film 11 for a Blu-ray Disc or the like is generally manufactured by casting a solution that has been obtained by diluting a polycarbonate resin with a solvent onto a belt to form a film, but projections 10 may be formed on the surface of the protective film 11 manufactured.
In the case of forming a hard coating layer 12P on the surface of a protective film 11 having projections 10 thereon as described above, defects arise in the surface of the hard coating layer 12P nucleated by the projections 10, leading to deterioration of signal characteristics.
Moreover, when forming the hard coating layer 12P, in the case that foreign bodies such as dust or the like are attached to the surface of the protective film 11 and a coating agent for the hard coating layer 12P is applied on in this state, a similar problem arises.